Method and apparatus for thermal viscosity modulating a fluid stream

ABSTRACT

A method and apparatus for thermal viscosity modulating a fluid stream by time varying the temperature of the stream in response to an intelligence signal. The method and apparatus are useful for &#39;&#39;&#39;&#39;printing&#39;&#39;&#39;&#39; or forming an ink image of an original in black and white or color. In the preferred embodiment, a plurality of fluid printing ink streams are thermal viscosity modulated in response to an electrical signal which represents a scanned original. Each fluid ink stream corresponds to a resolution element across the serially or parallel scanned original. The image of the original is formed or &#39;&#39;&#39;&#39;printed&#39;&#39;&#39;&#39; on a suitable fluid receptor, such as paper, by depositing the fluid streams in varying amounts on the receptor according to the viscosity of each of the streams. The thermal viscosity modulation of the fluid stream is accomplished in a preferred embodiment by passing the fluid streams under pressure through capillaries each having a thin film electrical resistor formed on the inner wall thereof. The scanned original electrical signal is impressed across the capillary electrical resistor to heat the fluid ink stream in accordance with the signal. By varying the amount of heat, the viscosity of each stream is modulated as a function of the value of the corresponding resolution element of the original.

United States Patent 1191 Carley Feb. 5, 1974 METHOD AND APPARATUS FORPrimary ExaminerBernard Konick THERMAL VISCOSITY MODULATING A Attorney,Agent, or FirmChittick, Pfund, Birch, FLUID STREAM Samuels & Gauthier[76] Inventor: Adam Loran Carley, 45 Linnaean St., Cambridge, Mass.02138 [57] ABSTRACT [22] Filed: July 21, 1971 A method and apparatus forthermal viscosity modulating a fluid stream by time varying thetemperature [21] Appl' 164510 of the stream in response to anintelligence signal. The Related US. Application Data method andapparatus are useful for printing or [63] Continuation-impart 6f Ser.N0. 46,935, June 17, forming an ink image of an Original in black andWhite 1970, Pat. No. 3,741,118. or color. In the preferred embodiment, aplurality of fluid printing ink streams are thermal viscosity modu- [52][1.5. CI l78/6.6 R, 101/335, 346/1, lated in response to an electricalsignal which repre- 346/ 140 sents a scanned original. Each fluid inkstream corre- [51] Int. Cl. G0ld 15/18 sponds to a resolution elementacross the serially or [58] Field of Search... 346/1, 140, 76 R, 74 ES,75; parallel scanned original. The image of the original is 178/66 R,96; 219/21 1 formed or printed on a suitable fluid receptor, such aspaper, by depositing the fluid streams in varying [56] References Citedamounts on the receptor according to the viscosity of UNITED STATESPATENTS each of the streams. The thermal viscosity modulation 2,633,7964/1953 Pethick 346/74 ES ux g g g i i in a pgeferred 3,134,849 5/1964Frohbach 6:61 346/140x 0 y pas,smgt e Stream? er 3,161,882 12/1964Mullin 346 74 ES f caplnanes 9 having a thm film elecmcal 3,270,637 91966 Clark 346 140 ux reslstor formed on the Inner Wall thereof TheScanned 3,359,566 12/1967 Donalies 346/ 140 original electrical signalis impressed across the capil- 3,656,169 4/1972 Kashio 346/75 laryelectrical resistor to heat the fluid ink stream in 2,437,365 11/1949 3346/76 R accordance with the signal. By varying the amount of We1glet alheat viscosity of each stream is modulated as 3 2,556,550 6/1951 Murray346/1 function of the value of the corresponding l i element of theoriginal.

27 Claims, 8 Drawing Figures s l 22, 1 l8 SCANNER MEMORY V a /9 PRESSURE4, [0 SOURCE PAIENTEDFEB 14 3.790.703

sum 1 or 2 l6 .22, I I 2, f

' SCANNER v MEMORY k PRESSURE 1 SOURCE COMPUTER INVENTOR- ADAM L. CARLEYI PAIENIEUFEB 5:914

2 HF PRES E 30 S RCE C CK SHIFT REGISTER FIG-7 S CH INVENTOR' ADAM L.CARLEY Y METHOD AND APPARATUS FOR THERMAL VISCOSITY MODULATING A FLUIDSTREAM CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-Part application of my application Ser. No. 46,935,filed June 17, I970 for METHOD AND APPARATUS FOR ELEC- TRONICLlTHOGRAPI-IY now US Pat. No. 3,741,118.

BACKGROUND OF THE INVENTION technique which employs a plate on which theareas corresponding to the inked areas of the image have differentproperties than the other areas. An aqueousbased fountain solution isapplied to the plate and adheres only to the non-ink areas. An oil-basedink is then applied to the plate. The ink is repelled by the fountainsolution and adheres only to the ink-receptive areas of the plate. Theplate is then brought into contact with the paper (direct lithography)or with a resilient rubber blanket which in turn prints on the paper(offset lithography).

The second technique, letterpress, utilizes a plate on which areascorresponding to the inked section of the image are raised. When the inkis applied to the plate, the ink adheres to the raised portions only.The image is then printed by bringing the paper into contact with theinked plate.

The gravure technique employs a plate on which areas corresponding tothe inked section of the image are indented. The printing ink is appliedto the plate and then the plate is wiped with a doctor blade leavingprinting ink only in the indented portions. When the paper is broughtinto contact with the plate, it absorbs the ink from the indentedportions.

The printing processes described above all require that a plate beprepared prior to the printing process which contains in some permanentform the image to be printed. In practice, such plates are used onpresses repeatedly so as to rapidly produce many copies of the sameimage. However, it is not possible to introduce a new image withoutinterrupting the printing process to change the plate. This is not onlycostly from an equipment standpoint, but it is also expensive in termsof the down time for the printing press.

Recent advances in technology have produced a number of copyingtechniques. The various electrostatic processes, including xerographiccopying, employ techniques which do not involve a permanent plate, butinstead create a charged pattern on a photoconductor, such as, zincoxide or selenium, to which a powdered ink selectively adheres. Thephotoconductor is either on an intermediary, e.g., drum, or the paperitself. Unfortunately, the electrostatic processes have severallimitations: the electrostatic ink is much more expensive than printersink; the quality is noticeably inferior to conventional printing; and,the process is unacceptable for photographic work.

Photography or chemical imaging is a technique in which the variationsinvolve light-sensitive chemical reactions, heat sensitive chemicalreactions, possible intermediary images, developing reagents, chemicalimage transfers and the like. The per-print cost is relatively high andthe processes are generally slow and inconvenient. However, the qualityis good; especially when silver chemistry is employed.

Although each of the printing or imaging techniques discussed above issuitable for certain applications, the technical limitations andeconomic tradeoffs of each technique substantially preclude the use of asingle technique in a broad range of imaging applications. It is,accordingly, a general object of the present invention to provide a newmethod and apparatus for printing or imaging which obviates many of thetechnical limitations of the existing techniques and which providescompetitively acceptable economic tradeoffs.

It is a specific object of the present invention to provide a method andapparatus for modulating a fluid stream with an intelligence signal.

It is another specific object of the present invention to provide amethod and apparatus for printing an image of high quality at low costand at high speeds.

It is still another object of the invention to provide a method andapparatus for printing a visible image from an image in scannedelectronic form.

It is a further object of the present invention to provide a method andapparatus for printing which utilizes thermal viscosity modulation of astream of printing ink.

It is still a further object of the present invention to provide amethod and apparatus for printing which prints the same or differentimages in continuous sequence.

It is a feature of the invention that the above objects can be achievedwithout sacrificing the quality of the final printed image while at thesame time providing a competitive cost per-print/quality ratio.

These objects and other objects and features of the present inventionwill best be understood from a detailed description of a preferredembodiment thereof selected for purposes of illustration and shown inthe accompanying drawings in which:

FIG. 1 is a diagrammatic view in partial perspective and block diagramform illustrating the printing or imaging system of the presentinvention;

FIG. 2 is an enlarged detailed view showing the tip of the printing headin relation to the ink receiving paper;

FIG. 3 is a greatly enlarged view of a representative cross-sectiontaken through the tip of the printing head showing the capillary crosssection;

FIG. 4 is a simplified diagrammatic view of the ink distribution dystem;and,

FIGS. 5A and 5B are block diagrams of the circuitry employed in thermalviscosity modulating the stream of printing ink through the printinghead tip capillaries.

FIG. 6 is an alternative construction of the printing head illustratingthe use of conductive or electromagnetic radiation heating of theprinting ink; and,

FIG. 7 is still another alternative construction showing an air brush"transfer system and electrostatic means to facilitate ink transfer.

Turning now to the drawings and particularly to FIG. 1 thereof, there isshown in diagrammatic view and partial perspective and block diagramform a printing or imaging system constructed in accordance with thepresent invention. An original 10, such asa document or photograph,having an image or indicia 12 thereon is scanned by a conventionalscanner 14, such as, a flying spot scanner. The scanning action isindicated diagrammatically in FIG. 1 by the two arrows identified by thereference numeral 16. Other known scanning techniques also can be usedincluding parallel wire, TV and facsimile scanning of the original.

The output signal from the scanner 14 on line 18 comprises an electricalsignal having a characteristic which varies in accordance with the lightvalue of each element of the scanned original 10. The scanned electricalsignal on output line 18 constitutes an intelligence signal since itrepresents in electrical form the intelligence information of thescanned original 10. Alternatively, the intelligence signal can bedirectly generated by a computer 19.

The electrical intelligence signal on line 18 can be used directly toactuate a printing head assembly 20, as will be described in detailbelow, or it can be stored in a suitable memory 22 for subsequentutilization. In broad terms, the printing head assembly 20 comprises ameans for depositing a modulated fluid stream upon a suitable fluidreceptor. Expressed in printing technology, the printing head assembly20 controls the deposition of a printing ink 24 upon an ink receptor 26,such as, paper, or an intermediate ink transfer medium. The printing inkis contained in an ink reservoir 28 under pressure from a pressuresource 30. The ink reservoir is fluidly coupled to a printing head 32.The ink or fluid 24 is discharged in a modulated stream from theprinting head in accordance with the intelligence signal from scanner14. The apparatus for modulating the ink stream with the intelligencesignal will be discussed below in connection with FIGS. 2 through 5.

Vertical scanning, in the sense of TV signal scan, is provided atprinting station 34 by the relative movement of the printing headassembly 20 and the ink receptor 26. For the purposes of illustration,this relative movement is provided by a conventional belt-drive system,indicated generally by the reference numeral 35. Other variations in themeans for producing relative motion between the ink receptor and theprinting head assembly can be employed depending upon the desiredmachine configuration. For example, the printing head assembly can bemoved across the ink receptor. Similarly, a drum transport mechanism canbe used to move the ink receptor passed the printing head assemblyprinting station 34.

Looking at FIG. 2, there is shown in cross-section and greatly enlarged,a portion of the printing head 32. The printing head or "doctor" byanalogy with the use of that term in the gravure printing process, canbe considered as a knife blade extending across the width of the paperand angled with the moving ink receptor 26. The printing ink 24 isdelivered from the ink reservoir 26 through a plurality of capillaries36 which terminate at the printing head edge 38 in a correspondingplurality of capillary orifices 40.

The ink dispensing capillaries 36 deposit the ink onto the paper 26 inthe pattern of the original image 12. The number of capillaries dependsupon the desired resolution, the number of colors and the width of thepaper 26. At the present time, printing practice uses resolutions orscreens in the range of 60-200 elements per inch and one to four colorsexcept in specialized circumstances. For a standard, 8% inch wide page,

150 screen, and process color (four colors), the printing head 32 and5,100 capillaries. Under other circumstances, the number of capillaries36 could be under or over 10,000.

In the greatly enlarged side view of FIG. 2, four color capillaries 36a,36b, 36c and 36d are shown for each single picture element. These fourcolor capillaries, respectively, are fluidly connected to separatepressurized ink reservoirs containing yellow, blue, magenta, and blackink.

For purposes of illustration, only one such ink reservoir has been shownin FIG. 1. The four capillary orifices 40 are positioned as close aspossible to each other and to the forward or downstream edge of thedoctor blade in order to prevent the wet ink from being smeared by thedoctor blade.

It has already been mentioned that the ink flow through the capillariesis modulated in accordance with the scanned intelligence signal fromeither scanner 14, memory 22, or computer 19. The intelligenceinformation is impressed upon or modulates the printing ink 24 bythermal viscosity modulation. Thermal viscosity modulation of theprinting ink is accomplished by selectively heating the printing ink ineach capillary tube. Heat is applied to the ink by the wall of thecapillary which is partially or totally covered by a thin film resistor42. The electrical signal which represents the desired image isimpressed after the suitable amplification or other processing acrossthe resistor 42 causing ohmic heating thereof. Since both the thin filmresistor 42 and the ink itself have a relatively small thermal mass, theheat generated produces a rapid temperature change in the moving ink.Preferably, the entire length of the capillary tube is heated in unisonthereby causing the microscopic column of ink to suddenly accelerate dueto viscosity modulation.

Looking at FIG. 3, which is a view in cross-section of a capillary tubetaken perpendicularly to the direction of ink flow, it can be seen thatthe capillary tube 36 has an elongated rather than circularconfiguration. This shape is desirable in order to decrease the timerequired to thermal viscosity modulate the flowing ink. With thisstructural configuration, it is possible to obtain very rapid changes intemperature of the ink in the capillaries using frequencies in the audiorange.

The thermal mechanisms of the system are relatively straight forward.The flow rate through the capillary tube, ignoring end effects, is givenby where 1 is the viscosity, p is the pressure difference, G is a factorof dimension cm representing the geometry of the capillary, and F is theflow rate in volume/time if the viscosity is absolute (poises), ormass/time if the viscosity is kinematic (stokes).

The 1; of liquids decreases markedly when they are heated. For manyoils, viscosity can be varied by a factor of over 1,000 by varying thetemperature. Even water is six times thicker near freezing than nearboiling. By using a suitable vehicle for the ink, it is possible toproduce a thousand times more flow through a hot capillary than througha cold capillary with a continuous range in between. Current printingpractice indicates that a flow ratio of approximately 100:1 is requiredfor quality work. The ink flow can be shut off completely by turning offthe pressure or by lowering the capillary temperature to virtualsoldification of the ink. However, for purposes of illustration in thepresent invention, it is assumed that white" is an invisibly small inkflow, but not zero.

A variety of suitable vehicles can be used for the ink. Successful testshave been conducted using AMCD Copy Duplicator CD-l 18 ink sold by theCopy Duplicator Division of the AM Corporation, 1,200 Babbitt Road,Cleveland, Ohio. The ink vehicle, and the ink as a whole, should have awide dynamic range of viscosity as a function of temperature. Many oils,including some presently or previously used as vehicles in conventionalprinting inks have the desired characteristics. These oils includemineral oils, castor oil and linseed oil. It is also possible, ofcourse, to use a water vehicle albeit with a much more limited dynamicrange of viscosity as a function of temperature.

Each thin film resistive element 42 is surrounded by an electricalinsulator 44 and a heat sink 46 which provide the dominate mode of heatloss, as well as, electricalinsulation and mechanical strength. The heatsink 46 is maintained at or below the lowest temperature desired andpreferably is constructed from a metal and is shared by all of thecapillaries 36. A separate fluid cooling system (not shown) can beemployed to remove heat from the heat sink 46 if the signal power levelsproduce more heat than can be dissipated by the heat sink.

The insulator 44 conducts heat from the capillary to the heat sink andhas a preselected thickness or thermal resistance which is compatablewith the other physical parameters of the system. The choice of variousphysical parameters determines the time response of the printing orimaging system. For faster time response, the capillaries are narrower,the pressure is higher, the insulator thinner and more power isdissipated by the thin film resistor 42 and absorbed by the heat sink.For a slower response, these parameters are less restrictive.

Referring now to FIG. 4, there is shown in simplified diagrammatic viewan ink distribution system for the present invention. As mentionedpreviously, the ink reservoir 28 is pressurized by a pressure source 30.The printing ink 24 in reservoir 28 passes through a ink filtrationsystem indicated generally at 48, in order to remove any particulatematter which might clog the printing head capillaries. The filtered inkpasses into a final ink chamber 50 and then down into each of thecapillaries 36. If desired, the printing ink 24 can be preheated bypassing the ink through an electrically powered preheating station 52.The use of the preheating technique minimizes or substantiallyeliminates end effects in the capillaries.

The circuitry employed in the thermal viscosity modulation of the streamof printing ink through the printing head tip capillaries is shown inblock diagram form in FIGS. 5A and 5B. Referring first to FIG. 5A, thereis shown the circuitry for a one dimensional scan. By optical meanswhich are not part of the invention, a line 54 of the original image 12is color separated into the three primary colors. Conventional devicessuch as dichroic mirrors, color filters or prisms can be employed toachieve the color separation of the image. The color separate image ofthe line 54 is focused by an optical system, indicatedrepresentationally and identified by the reference numeral 56, onto alinear arrangement of photocells 58 which transduce the line image intoelectrical signals. Although the electronics for only one primary coloris shown in FIG. 5A, it should be understood that the same circuitry isrepeated for the two other primary colors. The fourth color, black, doesnot require photocells 58, since its value can be calculated from theother colors, but may have them for reasons well-known in the televisionart.

Color matrixing and gamma adjustment are performed electrically byconventional circuits identified by the reference numeral 60. When theproper signal has been derived, it is amplified by power amplifiers 62which drive the capillary ohmic heaters 42. It will be appreciated thatwhile not explicitly shown, there is a polarity inversion involved inthe system since the resistors 42 are powered for black" and unpoweredfor white.

The circuit shown in FIG. 5B depicts in block diagram form theelectronics for a two dimensional scan. The image information issupplied as a scanned electronic signal such as a television signal. Ingeneral, the parameters of the scanned electronic signal, such asframe-rate, number of lines, differ markedly from a standard televisionsignal and the signal is noninterlaced. The signal can be generated in anumber of ways either directly by electronic equipment such as acomputer, or from video-tape or by a camera using electronic ormechanical scanning with or without image storage (integration) and witha scanned or unscanned light source. Conventional camera technology andelectronic signal generation and processing are employed in thepresentinvention and need not be described in detail. It is sufficientto note that some of the currently available camera technique which canbe employed to produce the scanned electronic signal include: imageorthicon, vidicon, flying-spot scanner, rotating mirrors, rotatingprisms, scanned laser light source and dichroic mirror color separation.

The television or signal parameters are selected for the speed, aspectratio, and resolution desired. Compared to standard 525 line televisionsignals, representative values for printing three 8 /z X l 1 inch copiesper second at lSO-screen resolution are: l/lO the frame rate; 10 timesthe resolved picture elements; and the same bandwidth.

In the case of color printing, the colors in the original are separatedand matrixed electronically to produce separate television signals foreach color ink used in the printing process. In addition, gray-scale(gamma) correction to the television signal is done before it is fed tothe printing unit. As shown in FIG. 5B, the television signal for thecolor in question comes in on a video bus 64 extending across the widthof the printing head 32. The signal is then descanned by well knowncircuit techniques such as, a shift register sampler comprising shiftregister 66 and samplers 68. Amplifiers and resistors 62 and 42respectively, perform the same function as in connection with FIG. 5A.Interconnections between the colors for matrixing purposes are notrequired, but the shift register 66 may be shared by all colors.

It will be appreciated that the electronic configuration shown in FIG.58 has the advantage that the image can be manipulated or stored forsubsequent usage while in electronic form. Manipulations includetransmission, storage, collating, masking, mixing, negative, contrastenhance, color correction and other specialized alterations such assequence numbering of printed forms. These manipulations of theelectronic signal are performed by conventional and well-known signalprocessing circuits or by computer.

FIG. 6 illustrates in diagrammatic form two altemative constructions ofthe printing head, which utilize conductive heating or electromagneticradiation absorptive heating of the printing ink. Two electrodes 70 and72 are positioned within the ink reservoir 28 at the entry to capillary36, which capillary is formed in an electrical insulator 74. Ifelectrically conductive printing ink is employed, the intelligencesignal modulated current flow through the ink between electrodes 70 and72 produces the desired thermal viscosity modulation. Suitable poweramplification can be provided in this mode of operation.

Electromagnetic radiation heating of the printing ink is another methodwhich can be utilized to achieve thermal viscosity modulation of theprinting ink. In this case, the intelligence signal on line 18 (or fromcomputer l9) modulates a source 76 of radio frequency energy. Themodulated rf is applied to the capillary electrodes 70 and 72 throughswitch means 78.

In order to obtain a smoother transfer of the ink from the capillaryorifices to the ink receptor 26, the preferred printing system utilizesan air brush and electrostatic transfer techniques. Looking at FIG. 7,there is shown in simplified form both the air brush and electrostatictransfer systems. The air brush system comprises a source 80 ofpressurized gas, such as air, and an outlet nozzle 82 positioned abovethe capillary orifices. The high velocity air stream exiting from nozzle82 forces the discharged ink from the capillaries downwardly onto thepaper ink receptor 26. The printing head is positioned with little or nogap between the head and the ink receptor. It will be appreciated thatthe air brush structure shown in FIG. 7 comprises what is known in theart as focused air brush.

Electrostatic ink transfer techniques can also be employed either aloneor in combination with the air brush system shown in FIG. 7 or thesimple friction transfer system depicted in FIG. 2. A high voltagepotential either DC or rapidly pulsed is applied between the inkreceptor 26 and the printing head 32. For purposes of illustration, thesource of the high voltage potential is illustrated in FIG. 7 as aconventional battery 84. However, it will be appreciated that otherconventional sources of a steady state or pulse DC potential can beemployed.

Having described in detail a preferred embodiment of my invention, itwill be appreciated that the invention can be used in a number ofapplications. Typically, such applications include photocopying,printing, computer printout, soft copy output with a non-drying inkprinted on an endless belt of washable material, facsimile, photographicprinting, direct photography, typewriter, and telegraphic printers.

What I claim is:

l. A method for thermal viscosity modulating a fluid stream with anintelligence signal comprising the steps of:

l. passing the fluid stream through a modulation station using a motivesource having sufficient mechanical admittance to permit thermallyproduced variations in the viscosity of the fluid stream to modulate theflow of said fluid stream; and,

2. time varying the temperature of at least a portion of the fluidstream at the modulation station in response to the intelligence signalwhereby said sig nal is impressed upon said fluid stream in the form ofthermally produced variations in the viscosity of the fluid stream whichcorrespondingly alter the flow of the fluid stream.

2. The method of claim 1 wherein the intelligence signal is anelectrical current and the temperature of said fluid stream is timevaried at the modulation station by passing the electrical currentthrough a resistive element that is located at said modulation stationand in thermally conductive contact with said fluid stream.

3. The method of claim 1 wherein said fluid is electrically conductiveand said intelligence signal is an electrical current which is passedthrough said fluid stream at said modulation station.

4. The method of claim 1 wherein said intelligence signal compriseselectromagnetic radiation which is absorbed by said fluid stream at saidmodulation station.

5. The method of claim 1 wherein said viscosity modulated fluid streamis deposited upon a fluid receptor.

6. A method of printing an image comprising the steps of:

l. generating an electrical signal which represents the image in scannedform;

2. passing at least one stream of printing ink through a modulationstation using a motive source having sufficient mechanical admittance topermit thermally produced variations in the viscosity of the fluidstream to modulate the flow of said fluid stream;

3. time varying the temperature of at least a portion of the printingink stream at the modulation station in response to the electricalsignal whereby said signal representation of the scanned image isimpressed upon the printing ink stream in the form of thermally producedvariations in the viscosity of the ink stream which correspondinglyalter the flow of the ink stream; and,

4. depositing at least a portion of said thermal viscosity modulatedprinting ink stream upon an ink receptor in accordance with the scannedform of said image.

7. The method of claim 6 wherein said electrical signal is generated byscanning an original which contains said image.

8. The method of claim 6 wherein said electrical signal is computergenerated.

9. The method of claim 6 further characterized by:

l. introducing said modulated ink stream into a rapidly flowing streamof gas; and,

2. directing the ink carrying gas stream against said ink receptorwhereby the thermal viscosity modulated ink is deposited on said inkreceptor.

10. The method of claim 6 further characterized by establishing anelectric potential between said modulation station and said inkreceptor.

11. An apparatus for printing an image comprising:

1. means for generating an electrical signal which represents the imagein scanned form;

2. printing ink reservoir means;

3. means for pressurizing said reservoir means, said pressurized inkreservoir means being a motive source having sufficient mechanicaladmittance to permit thermally produced variations in the viscosity ofthe' ink to modulate the flow of said ink;

4. means defining at least one capillary tube, said tube being fluidlycoupled at one end to said ink reservoir means and open at the other endto form an ink discharge orifice;

5. ohmic heating means positioned for thermal coupling to the inkpassing through said capillary tube;

6. means for applying said electrical signal to said ohmic heating meanswhereby said electrical signal is impressed upon said ink in the form ofthermally produced variations in the viscosity of the ink whichcorrespondingly alter the flow of the ink; and,

7. means for producing relative motion between an ink receptor and thedischarge orifice of said capillary tube corresponding to the scannedform of said image.

12. The printing apparatus of claim 11 wherein said capillary tubedefining means defines a plurality of capillary tubes which representone horizontal scan of said image and wherein said means for producingrelative motion produces a relative motion corresponding to the verticalscan of said image.

13. The printing apparatus of claim 11 wherein said means for generatingan electrical signal comprises an optical scanner.

14. The printing apparatus of claim 11 wherein said means for generatingan electrical signal comprises a computer.

15. The printing apparatus of claim 11 further characterized by focusedair brush means positioned to direct the thermal viscosity modulated inkexiting from the ink discharge orifice onto said ink receptor.

16. The printing apparatus of claim 11 further characterized by meansfor establishing an electrostatic potential between said capillary andsaid ink receptor.

17. The apparatus of claim 11 further comprising heat sink meansthermally coupled to the printing ink within said capillary.

18. A method of printing an image comprising the steps of:

1. generating an electrical signal which represents the image in scannedform;

2. passing at least one stream of printing ink through a modulationstation using a motive source having sufficient mechanical admittance topermit thermally produced variations in the viscosity of the printingink stream to modulate the flow of said printing ink stream;

3. time varying the temperature of at least a portion of the printingink stream at the modulation station in response to the electricalsignal whereby said signal representation of the scanned image isimpressed upon the printing ink stream in the form of thermally producedvariations in the viscosity of the ink stream which correspondinglyalter the flow of the ink stream; and,

4. entraining the thermal viscosity flow modulated printing ink streamin a gas stream and, thereafter 5. depositing the entrained printing inkstream on an 2. printing ink reservoir means; 3. means for pressurizingsaid reservoir means, said pressurized ink reservoir means being amotive source having sufficient mechanical admittance to permitthermally produced variations in the viscosity of the ink to modulatethe flow of said ink;

4. means defining at least one capillary tube, said tube being fluidlycoupled at one end to said ink reservoir means and open at the other endto form an ink discharge orifice;

5. electrical signal responsive heating means positioned for thermalcoupling to the ink passing through said capillary tube;

6. means for applying said electrical signal to said heating meanswhereby said electrical signal is impressed upon said ink whichcorrespondingly alter the flow of the ink; and,

7. means for producing relative motion between an ink receptor and thedischarge orifice of said capillary tube corresponding to the scannedform of said image.

20. The apparatus of claim 19 further comprising focused airbrush meanspositioned to direct the thermal viscosity modulated ink exiting fromthe ink discharge orifice onto said ink receptor.

21. The apparatus of claim 19 further comprising heat sink meansthermally coupled to the printing ink within said capillary.

22. An apparatus for printing an image comprising:

1. means for generating an electrical signal which represents the imagein scanned form;

2. printing ink reservoir means, said pressurized ink reservoir meansbeing a motive source having suffi cient mechanical admittance to permitthermally produced variations in the viscosity of the ink to modulatethe flow of said ink;

3. means defining a printing ink modulation station having an inlet andan outlet with the inlet being fluidly coupled to saidprinting inkreservoir means;

4. means with appreciable mechanical admittance for causing the ink topass through said printing ink modulation station;

5. electrical signal responsive heating means positioned for thermalcoupling to the printing ink passing through said printing inkmodulation station;

6. means for applying said electrical signal to said heating meanswhereby said electrical signal is impressed upon said printing ink inthe form of thermally produced variations in the viscosity of the inkwhich correspondingly alter the flow of the printing ink; and,

7. means for producing relative motion between an ink receptor and theoutlet of said printing ink modulation station corresponding to thescanned form of said image.

23. The apparatus of claim 22 further comprising focused airbrush meanspositioned to direct the thermal viscosity modulated ink exiting fromthe outlet of said printing ink modulation station onto said inkreceptor.

24. The apparatus of claim 22 further comprising heat sink meansthermally coupled to the printing ink at said printing ink modulationstation.

25. An apparatus for printing an image comprising:

1. means for generating an electrical signal which represents the imagein scanned form;

2. printing ink reservoir means, said pressurized ink reservoir meansbeing a motive source having sufficient mechanical admittance to permitthermally produced variations in the viscosity of the ink to modulatethe flow of said ink;

3. means defining a printing ink modulation station having an inlet andan outlet with the ink being fluidly coupled to said printing inkreservoir means;

4. means with appreciable mechanical admittance for causing the ink topass through said printing ink modulation station;

5. means for impressing said electrical signal upon the printing ink inthe form of thermally produced. I

variations in the viscosity of the ink which correspondingly alter theflow of the ink; and,

6. means for producing relative motion between an ink receptor and theoutlet of said printing ink dance with the scanned form of said image.

Patent No. 3,790,703

Dated February 5, 1974 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

' Column 8,

Column 2, line 54, "dystem" should be --system.

line 2, "and" should be -has--.

line 4, "100" should be --'l0'00--.

line 5, "the" second occurance should be -said-. line 55 "electric"should be -electrostatic".

Colunm 4, Column 4,

Column 10, line 28 delete "pressurized". Column 10, line 63 delete"pressurized". Column 10, line 11, after "said ink" insert in the formof thermally'produced ,variations in the viscosity of the ink-.

Column 11, line 2, "ink" should be -inlet-.

Signed and sealed this 26th day of November 1974.

(SEAL) Attest:

c. MARSHALL DANN McCOY M. GIBSON JRA'.

Commissioner of Patents Attesting Officer

1. A method for thermal viscosity modulating a fluid stream with anintelligence signal comprising the steps of:
 1. passing the fluid streamthrough a modulation station using a motive source having sufficientmechanical admittance to permit thermally produced variations in theviscosity of the fluid stream to modulate the flow of said fluid stream;and,
 2. time varying the temperature of at least a portion of the fluidstream at the modulation station in response to the intelligence signalwhereby said signal is impressed upon said fluid stream in the form ofthermally produced variations in the viscosity of the fluid stream whichcorrespondingly alter the flow of the fluid stream.
 2. time varying thetemperature of at least a portion of the fluid stream at the modulationstation in response to the intelligence signal whereby said signal isimpressed upon said fluid stream in the form of thermally producedvariations in the viscosity of the fluid stream which correspondinglyalter the flow of the fluid stream.
 2. The method of claim 1 wherein theintelligence signal is an electrical current and the temperature of saidfluid stream is time varied at the modulation station by passing theelectrical current through a resistive element that is located at saidmodulation station and in thermally conductive contact with said fluidstream.
 2. printing ink reservoir means, said pressurized ink reservoirmeans being a motive source having sufficient mechanical admittance topermit thermally produced variations in the viscosity of the ink tomodulate the flow of said ink;
 2. printing ink reservoir means; 2.passing at least one stream of printing ink through a modulation stationusing a motive source having sufficient mechanical admittance to permitthermally produced variations in the viscosity of the printing inkstream to modulate the flow of said printing ink stream;
 2. printing inkreservoir means;
 2. directing the ink carrying gas stream against saidink receptor whereby the thermal viscosity modulated ink is deposited onsaid ink receptor.
 2. printing ink reservoir means, said pressurized inkreservoir means being a motive source having sufficient mechanicaladmittance to permit thermally produced variations in the viscosity ofthe ink to modulate the flow of said ink;
 2. passing at least one streamof printing ink through a modulation station using a motive sourcehaving sufficient mechanical admittance to permit thermally producedvariations in the viscosity of the fluid stream to modulate the flow ofsaid fluid stream;
 3. means defining a printing ink modulation stationhaving an inlet and an outlet with The ink being fluidly coupled to saidprinting ink reservoir means;
 3. time varying the temperature of atleast a portion of the printing ink stream at the modulation station inresponSe to the electrical signal whereby said signal representation ofthe scanned image is impressed upon the printing ink stream in the formof thermally produced variations in the viscosity of the ink streamwhich correspondingly alter the flow of the ink stream; and,
 3. timevarying the temperature of at least a portion of the printing ink streamat the modulation station in response to the electrical signal wherebysaid signal representation of the scanned image is impressed upon theprinting ink stream in thE form of thermally produced variations in theviscosity of the ink stream which correspondingly alter the flow of theink stream; and,
 3. The method of claim 1 wherein said fluid iselectrically conductive and said intelligence signal is an electricalcurrent which is passed through said fluid stream at said modulationstation.
 3. means for pressurizing said reservoir means, saidpressurized ink reservoir means being a motive source having sufficientmechanical admittance to permit thermally produced variations in theviscosity of the ink to modulate the flow of said ink;
 3. means forpressurizing said reservoir means, said pressurized ink reservoir meansbeing a motive source having sufficient mechanical admittance to permitthermally produced variations in the viscosity of the ink to modulatethe flow of said ink;
 3. means defining a printing ink modulationstation having an inlet and an outlet with the inlet being fluidlycoupled to said printing ink reservoir means;
 4. means with appreciablemechanical admittance for causing the ink to pass through said printingink modulation station;
 4. means defining at least one capillary tube,said tube being fluidly coupled at one end to said ink reservoir meansand open at the other end to form an ink discharge orifice;
 4. meansdefining at least one capillary tube, said tube being fluidly coupled atone end to said ink reservoir means and open at the other end to form anink discharge orifice;
 4. entraining the thermal viscosity flowmodulated printing ink stream in a gas stream and, thereafter
 4. Themethod of claim 1 wherein said intelligence signal compriseselectromagnetic radiation which is absorbed by said fluid stream at saidmodulation station.
 4. means with appreciable mechanical admittance forcausing the ink to pass through said printing ink modulation station; 4.depositing at least a portion of said thermal viscosity modulatedprinting ink stream upon an ink receptor in accordance with the scannedform of said image.
 5. means for impressing said electrical signal uponthe printing ink in the form of thermally produced variations in theviscosity of the ink which correspondingly alter the flow of the ink;and,
 5. The method of claim 1 wherein said viscosity modulated fluidstream is deposited upon a fluid receptor.
 5. ohmic heating meanspositioned for thermal coupling to the ink passing through saidcapillary tube;
 5. electrical signal responsive heating means positionedfor thermal coupling to the ink passing through said capillary tube; 5.electrical signal responsive heating means positioned for thermalcoupling to the printing ink passing through said printing inkmodulation station;
 5. depositing the entrained printing ink stream onan ink receptor in accordance with the scanned form of said image. 6.means for applying said electrical signal to said heating means wherebysaid electrical signal is impressed upon said printing ink in the formof thermally produced variations in the viscosity of the ink whichcorrespondingly alter the flow of the printing ink; and,
 6. means forapplying said electrical signal to said heating means whereby saidelectrical signal is impressed upon said ink which correspondingly alterthe flow of the ink; and,
 6. means for applying said electrical signalto said ohmic heating means whereby said electrical signal is impressedupon said ink in the form of thermally produced variations in theviscosity of the ink which correspondingly alter the flow of the ink;and,
 6. A method of printing an image comprising the steps of:
 6. meansfor producing relative motion between an ink receptor and the outlet ofsaid printing ink modulation station corresponding to the scanned formof said image.
 7. The method of claim 6 wherein said electrical signalis generated by scanning an original which contains said image.
 7. meansfor producing relative motion between an ink receptor and the dischargeorifice of said capillary tube corresponding to the scanned form of saidimage.
 7. means for producing relative motion between an ink receptorand the discharge orifice of said capillary tube corresponding to thescanned form of said image.
 7. means for producing relative motionbetween an ink receptor and the outlet of said printing ink modulationstation corresponding to the scanned form of said image.
 8. The methodof claim 6 wherein said electrical signal is computer generated.
 9. Themethod of claim 6 further characterized by:
 10. The method of claim 6further characterized by establishing an electric potential between saidmodulation station and said ink receptor.
 11. An apparatus for printingan image comprising:
 12. The printing apparatus of claim 11 wherein saidcapillary tube defining means defines a plurality of capillary tubeswhich represent one horizontal scan of said image and wherein said meansfor producing relative motion produces a relative motion correspondingto the vertical scan of said image.
 13. The printing apparatus of claim11 wherein said means for generating an electrical signal comprises anoptical scanner.
 14. The printing apparatus of claim 11 wherein saidmeans for generating an electrical signal comprises a computer.
 15. Theprinting apparatus of claim 11 further characterized by focused airbrush means positioned to direct the thermal viscosity modulated inkexiting from the ink discharge orifice onto said ink receptor.
 16. Theprinting apparatus of claim 11 further characterized by means forestablishing an electrostatic potential between said capillary and saidink receptor.
 17. The apparatus of claim 11 further comprising heat sinkmeans thermally coupled to the printing ink within said capillary.
 18. Amethod of printing an image comprising the steps of:
 19. An apparatusfor printing an image comprising:
 20. The apparatus of claim 19 furthercomprising focused airbrush means positioned to direct the thermalviscosity modulated ink exiting from the ink discharge orifice onto saidink receptor.
 21. The apparatus of claim 19 further comprising heat sinkmeans thermally coupled to the printing ink within said capillary. 22.An apparatus for printing an image comprising:
 23. The apparatus ofclaim 22 further comprising focused airbrush means positioned to directthe thermal viscosity modulated ink exiting from the outlet of saidprinting ink modulation station onto said ink receptor.
 24. Theapparatus of claim 22 further comprising heat sink means thermallycoupled to the printing ink at said printing ink modulation station. 25.An apparatus for printing an image comprising:
 26. The apparatus ofclaim 25 further comprising heat sink means thermally coupled to theprinting ink at said printing ink modulation station.
 27. The apparatusof claim 25 further comprising means for entraining the thermalviscosity modulated printing ink in a gas stream with said entrainedprinting ink being deposited upon said ink receptor in accordance withthe scanned form of said image.